Microwave oven



FIG. 1 is a perspective view of a microwave oven showing the present design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a left side elevational view thereof; and,

FIG. 5 is a right side elevational view thereof. 

I claim the ornamental design for a microwave oven, as shown and described. 